Sink or swim?

January 14, 2011 4:06 PM

What can you tell a flatlander about living amongst landslides, sinkholes, and Karst topography?

I've long lived in very flat areas, but I recently moved to the metro east area of St. Louis in Illinois. My husband and I are looking for a house along the bluffs in that area that has a couple acres. We've now found a place we like, but we are both concerned because it is closely located to some sinkholes. They aren't on the property, but they next to the road that links us to the main road.

The property itself is mostly flat, but sloped. The area isn't close enough to a cliff or any major depression that I'm worried about landslides, but I am worried about future sinkholes. I've looked at this Sinkhole Plain Area Assessment from the Illinois DNR and from what I can tell the whole area is prone to this kind of activity.

What I'm wondering is if we will be more at risk because the area immediately east of us has sinkholes or if the risk is more or less constant. Of course, some of this might be land specific so my next question was is there anyone who does land inspections? I know this wouldn't fall under a home inspection, but I wasn't sure who to contact to find more about this particular property. The place looks nice but I'd hate for it to fall into a sink! If you think I'm completely too worried about this let me know because honestly, I'm used to ground that stays where it is supposed to.

posted by aetg to home & garden (6 answers total)

You are looking for geotechnical/soils engineer. Just be sure to tell them exactly what you want them to be looking for, so that you don't spend money on aspects of a geotech report that you don't care about (soil bearing capacity, etc)
posted by misterbrandt at 4:19 PM on January 14, 2011

You might also be able to get a geologist from a local University to come out and take a look. They likely do not have liability insurance, in case a sinkhole does open up.
posted by misterbrandt at 4:20 PM on January 14, 2011

I bought a house in a hillside area, and it was recommended that we get a geological inspection report done during escrow. I presume you could get the same thing, but with a different focus (ours was focused on landslide risk). Your realtor or a regular home inspector may have referrals to companies they have worked with before, but since sinkholes sound like a feature of the area, I'm sure there are plenty of local companies that specialize in doing this.
posted by Joh at 4:24 PM on January 14, 2011

What's the water use and withdrawal like where you're moving? If you're in an agricultural (stock ranching or farming) area or one with commercial bottlers of spring water, knock on some doors and ask the neighbors, or simply run away.

Ask a Floridian (speaking of flatlanders and karst topography) about excessive withdrawals encouraging sinkhole activity.
posted by toodleydoodley at 5:09 PM on January 14, 2011

Joh-How did the report affect the homeowner's insurance you got? Did you get a special addition for landslide risk?
posted by aetg at 2:58 PM on January 15, 2011

aetg, didn't seem to make any difference, the insurance companies never even asked about it, or were aware. Getting homeowners insurance is challenging here since its technically a landslide risk (geo report said no not really) and definitely a brushfire risk. So the geo report made no difference to them, but was helpful for me to assess the risk of buying here. I would have to go and look at the insurance policy to be sure, but I think we are not covered for landslides. I'm sure we could add it if we wanted to pay the extra though.

You need to get an idea of the risk of it happening, then see how much the insurance addition is and how much it covers. For example, we also chose to forgo earthquake insurance, because it is crazy expensive, and the deductible is so huge its basically worthless unless the entire house is turned to rubble. I would prefer to save that money every year and use it plus savings to rebuild if something like that happened, instead of giving it to the insurance company.

Talk to people in the neighborhood, ask them if they have insurance coverage for such an event, if they have heard of any actual damage from sinkholes in the area.
posted by Joh at 3:29 PM on January 15, 2011